Integrated circuit devices such as microprocessors and memory chips are typically connected to circuit boards by soldering the package that contains the microprocessor or memory chip to a circuit board. However, this type of connection mechanism makes upgrading of integrated circuit devices difficult and expensive.
Recent prior art methods allow for connecting a microprocessor to a circuit board such that the microprocessor may be easily replaced. One of these recent prior art methods includes the use of a microprocessor package which includes a land grid array and an interconnect socket which includes interconnects corresponding to the contacts of the land grid array. The microprocessor fits within the interconnect socket and overlies a grid array formed on a circuit board. A connection system is then used to press the microprocessor and the interconnect socket tightly against the grid array of the circuit board so as to make electrical contact between the microprocessor and the circuit board.
Prior art connection systems for pressing the microprocessor and the interconnect socket against the circuit board include the use of a top plate which overlies the microprocessor. Screws pass through openings in the top plate and pass through corresponding openings in the circuit board so as to engage openings in a backplate. As the screws are tightened, the top plate is pulled towards the backplate and the circuit board so as to press the microprocessor and the interconnect socket against the circuit board. Each screw is typically hand tightened or tightened using a power driven screwdriver. The compression of the assembly is typically controlled by tightening the screw to a specific depth or by torque.
In order to assure an adequate connection, one hundred to two hundred pounds of pressure must be applied to the microprocessor. Over tightening can damage the microprocessor and/or the circuit board. Under tightening causes contact failure or intermittent contact failure. Since hand tightening of the screw or tightening using a power driven screwdriver controls the pressure applied in prior art connection systems, compression is not consistent. This leads to damage to microprocessors and circuit boards, and can cause contact failure or intermittent contact failure.
Another problem with prior art systems is the heat generated by integrated circuit devices of the computer. In particular, there is a need to cool integrated circuit devices such as microprocessors and memory chips. Prior art systems typically include heat sinks for conducting heat away from individual electronic components and integrated circuit devices. These prior art heat sinks are typically formed of a thermally conductive material such as aluminum and they typically include extended surfaces or "fins" for conducting heat away from the device to be cooled.
Prior art computer systems typically use individual heat sinks which are disposed over individual integrated circuit devices for conducting heat away from each integrated circuit device. These prior art heat sinks are typically made of a highly thermally conductive material such as aluminum. Extended surfaces typically extend from the top of each heat sink so as to conduct the heat away from the heat producing integrated circuit device. Cooling fans which attach to the chassis of the computer are often used to circulate air over the extended surfaces so as to conduct heat away from individual heat sinks.
Recent prior art systems have combined a compression coupling mechanism with heat conduction structures by using the top surface of the compression coupling mechanism as a heat sink. In these prior art systems, extended surfaces are typically formed on the top of the compression coupling mechanism. However, such systems are typically compressed by using screws which pass through the top plate, through the circuit board and through a backplate. The backplate engages the threads of the screws so as to hold the screw in place. Each screw is typically hand tightened or tightened using a power driven screwdriver. The compression of the assembly is typically controlled by tightening the screw to a specific depth or by torque. Since hand tightening of the screw or tightening using a power driven screwdriver controls the pressure applied in prior art connection systems, compression is not consistent. Thus, these systems still may damage the integrated surface device and may give incomplete or intermittent contact between integrated circuit devices and circuit boards.
Another problem associated with prior art computer systems is the radio frequency (RF) emissions from integrated circuit devices. These RF emissions cause electromagnetic interference (EMI) which causes interference in other electronic circuits and electronic devices. Typically, an EMI shield is used to reduce RF emissions. This EMI shield typically takes the form of a full size chassis which extends around the entire electronics compartment of the computer. The chassis is typically made of metal. The full size chassis is expensive to manufacture. In addition, in order to effectively shield RF emissions, the chassis must completely enclose the RF producing components. This makes connection to external devices and insertion and removal of removable media such as floppy disks, computer disks, tape storage media and digital video disks difficult. In addition, it is difficult and expensive to manufacture and install on/off buttons, switches and indicator lights which do not violate the EMI shielding requirements. Though the use of a chassis to shield external electronic devices satisfies governmental EMI shielding requirements and prevents interference with external electronic devices, such a system does not shield electronic devices within the computer chassis. Thus, electronic devices and circuits within the computer chassis are subjected to EMI interference.
Manufacture and installation of separate heat sinks, an EMI shielding chassis, and a separate compression coupling mechanism is expensive and time consuming. What is needed is an inexpensive EMI shield which gives good EMI shielding and which minimizes or eliminates electromagnetic interference within the chassis of the computer. In addition, a method and apparatus for achieving uniform and constant connection between a microprocessor and a circuit board is needed. Furthermore, an effective and inexpensive heat sink is needed. Both the heat sink and the EMI shield and the compression coupling mechanism need to allow for the coupling of on/off switches, removable storage media and the replacement of microprocessors and other integrated circuit devices. The present invention provides a solution to the above needs.